﻿<p><em>IfcGeometricRepresentationSubContext</em> defines the context that applies to several shape representations of a product being a sub context, sharing the <em>WorldCoordinateSystem</em>, <em>CoordinateSpaceDimension</em>, <em>Precision</em> and <em>TrueNorth</em> attributes with the parent <em>IfcGeometricRepresentationContext</em>.</p>

<p>The <em>IfcGeometricRepresentationSubContext</em> is used to define semantically distinguished representation types for different information content, dependent on the representation view and the target scale. It can be used to control the level of detail of the shape representation that is most applicable to this geometric representation context. In addition the sub context is used to control the later appearance of the <em>IfcShapeRepresentation</em> within a plot view.</p>

<blockquote class="note">
NOTE&nbsp; If the <em>IfcShapeRepresentation</em> using this sub context has<em> IfcStyledItem</em>'s assigned to the <em>Items</em>, the presentation style information (e.g. <em>IfcCurveStyle</em>, <em>IfcTextStyle</em>) associated with the <em>IfcStyledItem</em> is given in target plot dimensions. For example, a line thickness (<em>IfcCurveStyle.CurveWidth</em>) is given by a thickness measure relating to the thickness for a plot within the (range of) target scale.
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<p>Each <em>IfcProduct</em> can then have several instances of subtypes of <em>IfcRepresentation</em>, each being assigned to a different <em>IfcGeometricRepresentationSubContext</em>). The applicable values for the inherited <em>ContextIdentifier</em> attribute shall be identical to the <em>RepresentationIdentifier</em> attrubute defined at <em>IfcShapeRepresentation</em>.</p>

<blockquote class="note">
NOTE&nbsp; The provision of a model view (<em>IfcGeometricRepresentationContext.ContextType</em> = 'Model') is mandatory. Instances of <em>IfcGeometricRepresentationSubContext</em> relate to it as its <em>ParentContext</em>.
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<blockquote class="example">
EXAMPLE&nbsp; Instances of <em>IfcGeometricRepresentationSubContext</em> can be used to handle the multi-view blocks or macros, which are used in CAD programs to store several scale and/or view dependent geometric representations of the same object. The application can then choose the most appropriate representation for showing the geometric shape of the product, depending on the target view and scale.
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<blockquote class="history">
HISTORY&nbsp; New entity in IFC2x2.
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